Inflammation is fundamentally a protective mechanism;however, in allergic, autoimmune, and autoinflammatory disorders, alterations in the inflammatory processes result in disease. Inflammation can be initiated by such varied stimuli as pathogens and generalized cold exposure, and the innate immune system plays a role in these responses. Although recently the focus of intense study, the innate immune system is not well characterized. Familial cold autoinflammatory syndrome (FCAS) is an excellent model for the study of innate immunity and the immune system's response to physical stimuli. Study of the molecular mechanisms of FCAS has led to novel effective cytokine targeted therapies for the disorder. The mutated gene (CIAS1) and protein (cryopyrin) identified in FCAS may play an important role in more common inflammatory disorders such as rheumatoid arthritis and gout. Our identification of CIAS1 and cryopyrin has brought attention to a new family of intracellular innate immune receptors known as Nucleotide binding domain-Leucine rich Repeats (NLRs) that share common features with Toll-like receptors which are integral in innate immune response. Cryopyrin's role in innate immunity is under study, and cryopyrin has been shown to sense a variety of exogenous and endogenous danger signals. Cryopyrin's extensive alternative splicing may be one mechanism in the innate immune system for creating specificity for multiple ligands. The main goal of this proposal is to delineate the processes through which cryopyrin mediates inflammation in response to cold and determine if this process is protective against pathogens. This will necessitate identification of the role of alternative splicing, especially as it relates to ligand specificity and protein function. The following lines of experimentation will be carried out: 1) In vitro and in vivo studies with both human and mouse models will be utilized to identify the molecular mechanisms through which cold mediates inflammatory responses;2) Systematic studies of the host-pathogen response will be performed to determine the effects of FCAS-associated cryopyrin mutations on in vitro mouse and human monocyte/macrophage response and systemic in vivo mouse response;3) Expression patterns, functionality, and ligand specificity of cryopyrin isoforms will be studied. Understanding the mechanisms of auto-inflammatory and innate immune responses will impact on human health for several reasons: 1) It will allow for the development of new targeted therapies for inflammatory conditions which currently have few effective treatments;2) It may provide insights into a means to improve resistance to infection;3) Understanding how a physical stimulus such as cold can trigger inflammation may lead to therapies that are protective against cold induced disorders.